Use Select Stitches 
to select and edit single stitches. Simply click a stitch and a box appears around it to show that it is selected.
It may be helpful to zoom in close enough to see the separate stitches.
Click and drag the box to move the stitch. If desired, use Delete 
to delete the stitch point.
Shortcuts
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Modify Tab:
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Keys: Alt, M, SS
Select a Series of Stitches
Click the first required stitch point, then hold down Shift (on the keyboard) and click the last required stitch point. The two stitches you click and all stitches between them will be selected. Click outside the block to make a new selection using this method.
To select several individual stitches, hold down Ctrl and click the desired stitches.
Alternatively, hold down Shift and use the left and right arrow keys to select a series of stitches.